The present invention is related to deposition apparatus in general and, in particular, to plating apparatus for plating material continuously on a strip of another material as the strip is transported continuously through the apparatus.
In the connector industry, for example, it is frequently necessary to plate a strip of material with gold, silver or other metal prior to forming it into connectors. This is necessary for providing a suitable electric interface between the formed connector and a mating connector and for providing surfaces which are not subject to corrosion. This plating is required only at the interface and not in the balance of the connector. Also for the prevention of corrosion and for the making of surfaces having good and long-term electrical conductivity, gold and the like are frequently required to be plated on strips in the fabrication of electrical connectors and the like.
When strips of metal were first plated for use in the fabrication of connectors and lead frames, they were plated entirely by submersion in a plating bath or the like. This practice was wasteful of material and, as the price of metals increased, became very costly. Later, when selective plating of the strips became desirable, because of the waste and increased costs attending the prior methods, masking tape and rotating wheels with center slots of widths to mask the strip came to be employed.
The use of masking tape or the like for masking a strip, however, is time consuming and consequently still costly. This is because of the labor and materials involved in placing the tape on the strip and the cleaning of the adhesives used on the tape from the unplated surfaces of the strip after the strip is plated.
Rotating wheels used for plating stripes on strips comprise a center slotted section in which is mounted one or more fluid jets for spraying the desired plating material on the strip as the strip is transported over at least a portion of the periphery of the wheel.
In rotating wheel assemblies in which the fluid jets rotate with the wheel, there are problems of uniformity of the stripe especially when one of the jets is clogged.
In general, rotating wheel assemblies are expensive to tool and require idler rollers, backing webs and the like which are necessary to feed a strip through the assembly.
Another form of apparatus which has been employed in plating stripes on strips is one in which the strip is stepped through the apparatus. As in the rotating wheel assemblies, if any of the jets used for spraying the plating material on the strip becomes clogged, a non-uniform plating results. The stepping type plating apparatus is also relatively slow and, consequently, has a relatively low throughput.